1. Field of the Invention
This invention relates to indicator molecules for detecting the presence or concentration of an analyte in a medium, such as a liquid, and to methods for achieving such detection. More particularly, the invention relates to copolymer macromolecules containing relatively hydrophobic indicator component monomers, and hydrophilic monomers, such that the macromolecule is capable of use in an aqueous environment.
2. Description of the Related Art
Indicator molecules for detecting the presence or concentration of an analyte in a medium are known. Unfortunately, many of such indicators are insoluble or sparingly soluble in water. For example, U.S. Pat. No. 5,503,770 (James, et al.) describes a fluorescent boronic acid-containing compound that emits fluorescence of a high intensity upon binding to saccharides, including glucose. The fluorescent compound has a molecular structure comprising a fluorophore, at least one phenylboronic acid moiety and at least one amine-providing nitrogen atom where the nitrogen atom is disposed in the vicinity of the phenylboronic acid moiety so as to interact intramolecularly with the boronic acid. Such interaction thereby causes the compound to emit fluorescence upon saccharide binding. See also T. James, et al., J. Am. Chem. Soc. 117(35):8982–87 (1995). However, the compound described in example 2 of U.S. Pat. No. 5,503,770 (having formula (6)) is substantially insoluble in water, and as a practical matter requires the presence of an organic solvent such as methanol in order to work in a liquid environment.
Lack of sufficient aqueous solubility is a severe problem when dealing with applications in an aqueous environment, for example, in vivo applications. Thus, there remains a great need for adapting insoluble or sparingly soluble indicators for use in aqueous environments.